Known in the art is a spark ignition type internal combustion engine provided with a variable compression ratio mechanism able to change a mechanical compression ratio and a variable valve timing mechanism able to control a closing timing of an intake valve, wherein an amount of intake air supplied to a combustion chamber is mainly controlled by changing the closing timing of the intake valve, the mechanical compression ratio is increased toward a maximum mechanical compression ratio as the amount of intake air supplied to the combustion chamber is reduced, the amount of intake air supplied to the combustion chamber is reduced as the closing timing of the intake valve is moved in a direction away from an intake bottom dead center toward a limit closing timing, when the closing timing of the intake valve reaches the limit closing timing, the amount of intake air supplied to the combustion chamber becomes a control limit intake air amount which is a control limit by the variable valve mechanism, and when the amount of intake air supplied to the combustion chamber is further reduced from the control limit intake air amount, a throttle valve is used to control the amount of intake air supplied to the combustion chamber, and, at this time, the closing timing of the intake valve is held at the limit closing timing (see Patent Literature 1).
In this internal combustion engine, if an acceleration operation is performed when the amount of intake air supplied to the combustion chamber is smaller than the control limit intake air amount, that is, when the amount of intake air supplied to the combustion chamber is controlled by the throttle valve, to obtain the best fuel consumption, regardless of the degree of acceleration, first, the throttle valve is opened toward full opening, next, when fully opening the throttle valve, the movement of the closing timing of the intake valve from the limit closing timing in a direction approaching the intake bottom dead center so as to increase the amount of intake air supplied to the combustion chamber is started.